This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In life two different RNA ligation pathways involved in RNA splicing can be pinpointed. The yeast type and the animal/archaeal type ligation pathway. While human mainly utilize the animal type RNA ligation pathway, many pathogens like Leihsmania and Trypanosome rely on the yeast-type tRNA ligation pathway. Hence the yeast type tRNA ligase is a good target to develop a medication against several tropical diseases. Identification of the archaeal RNA ligase should inspire the identification of the human tRNA ligase which has been described in literature as very unstable.